Mortality among employees of an Ontario factory manufacturing insulation materials from amosite asbestos

Our plain-English summary of Mortality among employees of an Ontario factory manufacturing insulation materials from amosite asbestos, by M.M. Finkelstein (American Journal of Industrial Medicine, 1989).

The study

• Author: M.M. Finkelstein
• Journal: American Journal of Industrial Medicine
• Published: 1989;15(4):477-81
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000880).

Abstract

The mortality of workers from an Ontario factory manufacturing amosite asbestos insulation materials under poorly controlled environmental conditions is reported here. Seven (58%) of 12 deaths among exposed workers 10 or more years after first exposure were due to malignancies; four (25%) were from lung cancer, and there were two deaths from peritoneal mesothelioma. Those dying from mesothelioma were 47 and 49 years of age. Three (25%) of 12 deaths were from respiratory disease, two were attributed to asbestosis (in men 42 and 53 years of ages), and one to pneumonia in a 54-year-old male.

In plain English

This brief communication reported deaths among workers at a factory in Point Edward, Ontario. From 1956 it made pipe insulation from South African amosite asbestos, adding asbestos-containing block insulation in the 1960s; asbestos production ended in 1974. In 1973 fiber counts reached 640 fibers per ml beside one machine operator. Because ownership changes prevented building a full worker list from company files, the author compiled 133 men from chest X-ray surveillance records. The list was matched to national death records, and deaths were compared with Ontario's general male population. Among workers classed as asbestos-exposed, 12 died 10 or more years after first exposure. Seven of these deaths were from cancer, including four from lung cancer and two from peritoneal mesothelioma, in men aged 47 and 49. Two deaths were attributed to asbestosis, in men aged 42 and 53. The author cautioned that the group was very small, the results very imprecise, and some deaths may have been missed. The author concluded that the findings confirm the extreme risk to workers in factories with poorly controlled amosite exposure.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Brief communication reporting a mortality (cohort) study: a person-years analysis comparing the factory cohort's deaths with death rates in the general male population of Ontario
• Who was studied: 133 men identified from Ontario Ministry of Labour chest X-ray surveillance records of employees of the Caposite/Holmes Insulation factory in Point Edward, Ontario. They were divided into three groups: 26 men in the rock wool plant (treated as unexposed or minimally exposed), 53 men exposed to asbestos for less than two years, and 54 men exposed for two years or longer. The end date of follow-up is not stated.
• Exposure: Amosite asbestos imported from South Africa. From 1956 the factory used it to make Caposite pipe insulation (55-60% amosite). During the 1960s it also began making Uniblock rock wool insulation that contained asbestos. Manufacture of asbestos-containing materials ended on March 22, 1974. In 1958 total dust measured 2.1 to 134 million particles per cubic foot. In 1973 fiber counts ranged from 1 fiber per ml near the office to 640 fibers per ml beside the disintegrator operator.
• Main results:
  • Among exposed workers, 7 of 12 deaths occurring 10 or more years after first exposure were due to cancer. Four of these were from lung cancer and two from peritoneal mesothelioma.
  • Both mesothelioma diagnoses and one of the four lung cancer deaths were confirmed at autopsy.
  • The two men who died of mesothelioma were 47 and 49 years old.
  • Among the exposed workers there were three respiratory deaths. Two were attributed to asbestosis, in men aged 42 and 53, and one to pneumonia, in a 54-year-old man.
  • There were no deaths from gastrointestinal cancer. The author noted that the study was too small to have much power to detect excess risk.
• The authors' conclusion: The author concluded that the observations confirm the extreme risk to workers in factories with poorly controlled exposures to amosite asbestos. The author also stated that the findings were similar to those reported for a New Jersey amosite factory after a corresponding follow-up interval.
• Limitations the authors state:
  • The population was very small, so the numerical results are very imprecise.
  • A complete roll of names and work histories could not be collected from company files because of several changes of company ownership, so the cohort was built from X-ray surveillance records. The share of the workforce that took the X-ray examination is unknown.
  • Identifying information on the clinic cards was poor, so some deaths may have been missed. The author therefore described the reported mortality ratios as lower-bound estimates.
  • Exposure groups were based on job titles on clinic cards and are not precise. Some men in the 'unexposed' rock wool group may have had substantial asbestos exposure.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Amosite, Lung Cancer, Peritoneal Mesothelioma, Mesothelioma.

Related studies

• Mortality among employees of an Ontario asbestos-cement factory — M.M. Finkelstein (1984)
• Mortality among long-term employees of an Ontario asbestos-cement factory — M.M. Finkelstein (1983)
• Analysis of mortality patterns and workers' compensation awards among asbestos insulation workers in Ontario — M.M. Finkelstein (1989)
• Asbestosis in long-term employees of an Ontario asbestos-cement factory — M.M. Finkelstein (1982)
• Techniques for tracing past employees. An example from an asbestos factory — M.L. Newhouse, J.M. Williams (1967)
• Malignant mesothelioma among employees of a Connecticut factory that manufactured friction materials using chrysotile asbestos — M.M. Finkelstein, C. Meisenkothen (2010)

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